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Catalina/Capri 25/250 Sailor's Forums

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Depth Meter

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knightwind
Navigator

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Canada
114 Posts

Initially Posted - 05/11/2008 : 17:24:06

I hooked up a battery to my boat today and found the depth meter to be quite erratic. The PO says he has this gain adjuster on it so he can set the depth to show the distance from the bottom of the keel as opposed to the hull. Turning the dial makes the needle waver around all over the place but doesn't settle on the correct depth by any means. The needle will also move if I wiggle the input RCA jack (notice the loose and open connection. Moving the iwres doesn't have any effect so they seem sound but moving the whole connector does affect the needle.
It seems to be a "Electro Marine Systems model U?5?"
Here's some pic's.

Help me get this working guys. We're outta money.
And where's the sender access located?

-Peter

Peter Keddie
Turkey Point, ON
79 Catalina 25 Fixed Keel #1050

Edited by - on

Voyager
Master Marine Consultant

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USA
5420 Posts

Response Posted - 05/11/2008 : 18:38:19

Peter -
I don't know much about your model. Mine, which is also an antique (but a digital antique rather than an analog model) has the electronics built into the display instead of in a separate box like yours.

DISCLAIMER: working with 12 volt systems is pretty safe, however these systems can cause very hot short circuits that can burn you and/or start a fire. Never work on energized circuits if you have metal tools in your hands. Further, never work on energized circuits if you are wearing a metal bracelet, wristwatch or ring and it completes a circuit next to your skin, as you can receive a severe burn.

Basic stuff would be:
1. Check the connections for corrosion and broken wires inside the insulation. There might be oxidation on the metallic surfaces or gunk build-up between the connector lugs and the screw terminals.

2. If the connector lugs are old, you should replace them. They are cheap. Cut the old ones off, strip back the insulation 1/2" and put the new ones on. Crimp them down good with a proper crimping tool.

3. On the screw terminal, back the screws out all the way and hit the metal with a thin strip of light sandpaper to shine them up.

[There is the slim chance that the electrical wires coming from the screw terminal connector body into the electronic components inside the control box are intermittent. If you can look inside, check to see whether any of these connections is obviously cracked or disconnected]

4. Looking at that coaxial cable with the RCA connector (consumer audio plug), the bend behind the connector looks very tight, so you may have an intermittent connection or broken wire inside the insulation going on there.

Some wire of this type has a stranded center conductor which is less likely to break, but other coax has a solid center conductor, which will snap off after several bends due to metal fatigue.

Replacement of these connectors is straightforward provided you have a Radio Shack nearby and can solder. You can simply replace the connector on the end of the coax.

5. Inside the RCA receptacle (female), make sure it has shiny contacts, as this could cause an intermittent connection. Judicious use of sandpaper is advised. Clean out the grit with a Q-tip afterward.

6. Follow the coax cable down to the transponder. It will likely be a through-hull fitting under the floor somewhere. Some of these have an integral cable - meaning there is no visible connector on the outside of the body. This type is hopeless unless there is a way to dig inside and fix the connection somehow. Others have a similar RCA plug. You can check and replace this RCA plug the same way as above.

7. If the coax cable is swimming in bilge water, water could have infiltrated the cable. This would call for a replacement cable, which ain't rocket science, so long as there are RCA connectors on both ends.

Again, Radio Shack or home electronics component dealer of choice, and purchase a sheilded audio coax cable (cannot be speaker wire) of the proper length and install it.

If you have to build a cable, you're best off NOT using TV coax [aka cable TV wire] as it has a solid center conductor. You need audio coax cable (like for your electric guitar) that you can solder the RCA connectors onto.

I don't think cable impedance is important (the old cable may be marked 50 Ohm, 75 Ohm, 300 Ohm or something else), but if you can match old and new, you might be better off.

Last comment, try the simple things first before looking to replace coax.

Since you mention it is wiggle sensitive, I'd start with the terminal strip, associated cables and the RCA plug going into the box.

Edited by - on

quilombo
Captain

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USA
301 Posts

Response Posted - 05/11/2008 : 21:12:11

I have a sender that looks like it will fit your gauge, lemme know if your interested

Edited by - on

delliottg
Former Mainsheet C250 Tech Editor

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USA
4479 Posts

Response Posted - 05/11/2008 : 22:12:43

This may be a stupid question. Is the boat in the water? If you're shooting a signal into air, you're never going to get a proper reading.

Edited by - on

knightwind
Navigator

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Canada
114 Posts

Response Posted - 05/11/2008 : 22:26:51

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by delliottg
 This may be a stupid question. Is the boat in the water? If you're shooting a signal into air, you're never going to get a proper reading.
<hr height="1" noshade id="quote"></blockquote id="quote">
Yes. She's in the water. 5-6 feet.
Where is the access panel for the senders again? forward bilge cover?

Edited by - on

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 05/12/2008 : 06:34:09

What make is your unit? I had SR Mariner redo our gauges with great success for less than I thought it would cost. The trim ring and size of yours looks a lot like ours.

The sending unit is wherever the PO thought was a good spot, from what I've heard. On ours, it is under the port side, where the bottom of the boat flattens out before heading into the keel. I am not sure if you can reach our sending unit by removing the cushions on the settee or not.

I have heard of a number of people buying a fishfinder with a sending unit they just hang over the side of the boat. This is a cheap way around the problem without having to get at the old unit at all.

Edited by - on

quilombo
Captain

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USA
301 Posts

Response Posted - 05/12/2008 : 17:12:19

should the sender make any noise when operating or is it quiet

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 05/12/2008 : 17:37:11

Guglielmo, you shouldn't hear anything from the transducer (sender/sounder).

Peter: Bruce covered the connection issues... Regarding accuracy, did you by any chance put bottom paint on the oudside of the transducer? Since you're not sure where it is, I'm suspicious... (Mine was under the forward port seat of the dinette interior.) You should use a special transducer paint on it--available in spray cans and little plastic bottles. If regular paint is on there--maybe several layers--you can carefully sand it down to the plastic surface of the transducer and then apply a thin coat of the special paint. (If you're launched for the season, "next year..."

)

Edited by - Dave Bristle on 05/12/2008 17:46:03

sweetcraft
Admiral

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USA
816 Posts

Response Posted - 05/12/2008 : 23:20:48

I have the SR Mariner which did get hooked up reverse once and it would never stop counting until rewired. It didn't hurt the unit as it has worked for many years afterward. The loose connection idea is sure worth a look. I put the sender in a mass of clear silicone inside the hull under the shelf just inside the port side of the forward berth.

Edited by - on

OLarryR
Master Marine Consultant

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USA
3477 Posts

Response Posted - 05/13/2008 : 05:10:16

If the loose connection troubleshooting and other easy, inexpensive solutions do not work out, I would consider a mod going to a fishfinder. While there is cost going this route, it may not be as expensive as you may think compared to repairing the old meter. The costs may be comparable. There are so many fishfinders on the market that the prices for some of the low end models is fairly reasonable. You may be able to pick one up for say $150. (I just checked West Marine Online and they have 5-6 models priced $89-$169.) What raises the cost above fixing the old meter is the method used to hook up the fishfinder. Some have made their own mounts. I covered the old meter hole with starboard and also mounted a starboard inside the cabin but what raised my cost was I preferred going with a RAM Swing mount versus making my own support for the fishfinder. But the transducers these days, many buy the fishfinders with transducers that can easily be mounted flush with the hull and not use a thru-hull.

Once again, hope your fix for the existing depthfinder turns out to be a loose connection but I had an SR Mariner depthfinder that was basically non-working and rather than invest the money into fixing an old unit, I put the money into a new fishfinder. The fishfinder has major benefits for me sailing on a river where it gives a sense of the river contour. Anyway, just thought I would mention that if it comes down to deciding to spend $100+ for the depthfinder repair with the shipping back and forth versus buying new and mounting the transducer by just slapping a toilet bowl wax ring glob on the inside of the hull.

Edited by - OLarryR on 05/13/2008 05:21:22

knightwind
Navigator

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Canada
114 Posts

Response Posted - 05/13/2008 : 06:41:06

I remember seeing the through-hull speed paddle-wheel and depth transducer side by side on the bottom of the port side near the keel base. I think it was painted over.
If I replace it does water start bubbling in?
If I buy a fishfinder do I just mount a transducer on the floor of the hull? or does it have to go in a special through-hull thing? or does in stick on the bottom of the outside of the hull?

Edited by - on

OLarryR
Master Marine Consultant

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USA
3477 Posts

Response Posted - 05/13/2008 : 22:33:00

Peter,

The new transducer for a fishfinder or depthfinder can be mounted inside the hull under the VBerth area. It does not need a thru-Hull. Mfrs oftentimes indcate that they need to be attached on the inside with epoxy but many of us have tried a much simpler method that works and if no signal in the area you pick, this method allows a 1 minute change of location. Best of all, the cost of mounting the transducer is peanuts. You go to Home Depot and buy a toilet bowl wax ring. Then you pull off a glob of it and slap it down inside the hull...near the old depthfinder transducer will probably work fine. For me that is just inside the beginning of the VBerth area. Then you take the transducer and push it into the glob of wax and twist it back and forth to ensure there are no bubbles/crevices under it. Then push some of the wax up and over the perimeter/sides of the transducer. Hook up your wires and you are done.

If your fiddling with the wires on your old depthfinder does not yield good results and you decide to go the fishfinder route, ensure that the fishfinder you buy has a transducer that can be mounted inside the hull. They usually indicate so in the description. Basically, it just means that the transducer has a nice flat bottom facilitating an inside on the hull mounting. Then don't epoxy it...try the toilet bowl wax ring method. Here are some photos:

Edited by - on

Voyager
Master Marine Consultant

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USA
5420 Posts

Response Posted - 05/13/2008 : 22:36:44

And in a pinch, you can replace the old gauge with a 4" or 5" inspection port, or you can create a nifty custom job like Larry. I was wondering whether I should put a clock on the bulkhead instead, but who really needs to know what time it is when you're out sailing? Right?????

Edited by - on

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